Process to manufacture upper work roll products

ABSTRACT

A process for manufacturing an upper work roller for use in the deep rolling of crankshafts including the steps of: rough sawing tool steel to form a generally cylindrical wafer, heat treating said wafer to provide it with a desired hardness, grinding of said wafer to desired dimensions to form a properly dimensioned heat treated blank wafer, a second grinding of said wafer to form a finished shape of work roller, and vibratory finishing said roller to achieve a desired microfinish thereon.

FIELD OF THE INVENTION

This invention broadly relates to deep rolling of fillets of enginecrankshafts or other annular areas of metallic workpieces subject tohigh stress loads. More specifically, this invention relates to a newprocess for manufacturing an upper work roller for use in the deeprolling of crankshafts or like workpieces.

BACKGROUND OF THE INVENTION

The state-of-the-art is indicated by the following cited references:Gottschalk, U.S. Pat. No. 5,495,738; Gottschalk, et al., U.S. Pat. No.5,445,003; Bone, U.S. Pat. No. 5,493,761; Winkens, U.S. Pat. No.5,138,859; Berstein, U.S. Pat. No. 4,561,276; and Ostertag, U.S. Pat.No. 4,947,668.

Various machines and methods have been employed to strengthen and finishmetal workpieces such as the camshafts and crankshafts for internalcombustion engines. In many modern automobiles, engines have beendownsized for installation into smaller vehicles. Accordingly, withdownsizing of automotive vehicles and their components for reducingweights and improving fuel efficiency, smaller engines and crankshaftsare needed. To improve the fatigue strength and durability of downsizedcrankshafts, deep rolling of fillets and other circular joint areas isincreasingly important. Fatigue strength and durability of crank pinsand main bearing journals can be significantly increased by deep rollingcompressive stresses into the metal of the annular fillets between thepin journals and the adjacent counter weights or balancing webs.

In connection with the process for manufacturing the upper work rollersused in the deep rolling of crankshafts, such work rollers are expensiveto produce and the response time to fill an order for such work rollersis quite lengthy. Accordingly, those skilled in the art have long soughtan economical and efficient way to produce such work rollers. In thepast, there have occurred particular problems in the area ofadvantageously, economically, and promptly producing such work rollers.

One object of this invention is to provide a novel process formanufacturing work rollers which is economical, and can be carried outpromptly and expeditiously from a time saving viewpoint.

Another object of the present invention is to provide a novel processfor manufacturing work rollers that is of such versatility toadvantageously shorten the response time to an order.

Other objects, features and advantages of the present invention willbecome apparent from the subsequent description and the appended claims,taken in connection with the accompanying drawings (wherein likenumerals indicate like elements).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an in-line four cylinder crankshaft.

FIG. 2 is a sectional view showing the upper and lower work roller toolsengaging a journal of the crankshaft shown in FIG. 1.

FIG. 2a is a side view of the upper work roller tool of FIG. 2.

FIG. 3 is an enlarged plan view of a dimensioned, heat treated blankwafer.

FIG. 4a is an enlarged side view of a finished, shaped work roller.

FIG. 4b is an enlarged top view of the work roller of FIG. 4a.

FIG. 4c is an enlarged plan view of the work roller in FIG. 4a.

SUMMARY OF THE INVENTION

Briefly stated, the present invention comprises a process formanufacturing upper work rollers suitable for deep rolling crankshaftsor like workpieces, comprising the steps of rough sawing tool steel toform a generally cylindrical wafer, heat treating said wafer to provideit with a desired hardness, grinding said wafer to form a properlydimensioned heat treated blank wafer for use in forming the roller, asecond grinding of said wafer to form a finished shape of a heat treatedroller, and vibratory finishing said roller to achieve a desired microfinish thereon.

From another aspect, briefly stated, the invention comprises a processfor manufacturing an upper work roller for use in the deep rolling ofcrankshafts or like products, comprising the steps of: (a) retrieving apreviously heat treated and properly dimensioned generally cylindricalwafer from storage; (b) grinding of said wafer to form a finished shapeof a heat treated roller; and (c) vibratory finishing said roller toachieve a desired microfinish thereon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS AND BEST MODE OF CARRYING OUTTHE INVENTION

Referring now in greater detail to the drawings, FIG. 1 is a side viewof a crankshaft 10 with a rotational axis 11 about which the crankshaft10 will rotate when it is in an engine. The crankshaft 10 rotates aboutthe rotational axis 11 on main bearing journals 12 which are journaledin the engine block. The crankshaft 10 will have a pin journal 14 foreach piston of an engine. Each pin journal 14 journals a piston rod (notshown) for a piston.

FIG. 2 is a sectional view of an upper work roller tool 20 and a lowerwork roller tool 21 engaging and rolling the crankshaft 10 at a journalarea 12, 14 to form the laterally spaced annual fillets 16. By directinghigh forces to each work roller tool 20, 21, high and concentratedrolling forces are translated to the work roller 40. Upon engaging thecrankshaft 10 in journal areas 12, 14, the work rollers 40 of the upperwork roller tool 20 forms the laterally spaced annular fillets 16. Thisdeep rolling process strengthens the journals 12, 14 of the crankshaft10 to increase the life of a crankshaft 10 during engine operation.

FIG. 2a is a side view of the upper work roller tool 20. The roller tool20 comprises a rectangular main body 21 that has been formed to providean annular recess 22 that receives an annual cover plate 27. The coverplate 27 is secured to the main body 21 by threaded fasteners 28. Themain body 21 and cover plate 27 have aligned enlarged annular recesses29 to receive a cylindrical hub 23.

The roller tool 20 has a pair of L-shaped roller retainers 24 adjustablysecured to the lower end of the main body 21 by opposing adjustablethreaded fasteners 28. The retainers 24 have inboard ends which arerecessed to provide cages 26. When the retainers 24 are secured to themain body 21, the cages 26 support the work rollers 40 for floatingrotation generally about upwardly and outwardly an incline axis 42 sothat the working circumference 44 of the work rollers 40 extend to thelaterally spaced annular fillets 16 of the crankshaft journals 12, 14being rolled.

FIG. 3 is an enlarged plan view of a dimensioned heat treated blankwafer 30 of a generally cylindrical shape machined from tool steel.Wafers 30 of various dimensions are created to establish a well-stockedcollection of such wafers.

FIGS. 4a, 4b and 4c are different enlarged views of a finished shapedwork roller 40 with a specified working circumference 44 and an adjacentconical surface 46. The finished work roller 40 is machined from theblank wafer 30.

In accordance with the present invention, an efficient and economicalprocess for manufacturing upper work rollers comprises:

Rough sawing tool steel to form a generally cylindrical wafer.

A preferred embodiment of this invention has the tool steel selectedfrom the group CPM-REX 76, ASP-60 M-2, ASP-60 M-4 or any other similarlycomposited tool steel.

Heat treating rough sawed wafer to provide it with a desired hardness.

A preferred embodiment of the invention has the heat treating processperformed in a vacuum to enhance the heat treating step. Anotherpreferred embodiment of the heat treating step is to achieve a hardnessin the range of about 63 to about 70 on a Rockwell C scale.

Grinding said wafer to form a properly dimensioned heat treated blankwafer 30 as in FIG. 3. A preferred embodiment of the invention has awell stocked collection of said wafers 30 having a variety of blankwafers 30 dimensioned to different specifications.

Retrieving a previously heat treated and properly dimensioned generallycylindrical wafer from storage to begin steps for finally shaping wafer30.

Grinding the retrieved wafer a second time to form a finished shapedroller 40 pursuant to a customer's order. A preferred embodiment of theinvention has the second grinding step performed by a CNC (computernumeric controlled) centerless grinding machine.

Vibratory finishing said roller 40 to achieve a desired microfinishthereon.

A preferred embodiment of the invention includes laser etching thefinished roller 40 with information regarding identification, materialand heat treating hardness.

The technical advantages of the invention herein result in a process formanufacturing work rollers that is substantially more efficient and costeffective than previous methods for manufacturing such work rollers.Previous methods for manufacturing said work rollers performed the heattreating process only after an order was received from a customer. Theheat treating process substantially increases the length of timenecessary to send out a finished product from the date the order isreceived. If the heat treating process is performed "in house" theincrease in turn around time could be several days. However, if the heattreating process is performed by another company, potentially weeks arelost in processing a finished product.

In accordance with the present invention, the heat treating step isperformed before an order is received considerably decreasing the timeneeded to get the finished product delivered. Upon receiving an order, aheat treated wafer 30 is simply pulled from the stock with the requisitedimension specifications as stated in the order. The wafer isimmediately ready for the finishing steps to produce a finished workroller 40. When down time for assembly lines in the automotive businesscan incur daily figures in the hundreds of thousands of dollars, thesignificance of decreasing the time period for finishing the product isreadily appreciated.

Moreover, the efficiency and cost effective benefits reaped by thecustomer due to performing the heat treating process before an order isreceived is also applicable to the manufacturer. The manufacturerperforming the heat treating process who is not under the timeconstraints implicitly incurred from an order will be more efficient inmanaging his manpower. If manpower is not needed for other duties, theycan be used at the manager's discretion and leisure to perform the heattreating process to increase the stock of blank wafers 30.

Under the time constraints of an order, a manager may not have theluxury of efficiently utilizing this manpower. Manpower may have to bepulled from other projects that are in process, or the manpower may haveto perform overtime to finish an order in a timely fashion. Clearly,having already performed the heat treating process before an order isreceived lends itself to efficient use of manpower in the most costeffective manner.

While it will be apparent that the preferred embodiments of theinvention disclosed are well calculated to fulfill the objects, benefitsand advantages of the invention, it will be appreciated that theinvention is susceptible to modification, variation, and change withoutdeparting from the proper scope or fair meaning of this adjoined claims.

What is claimed is:
 1. A process for manufacturing an upper work rollerfor use in the deep rolling of crankshafts or like products, comprisingthe steps of:(a) rough sawing tool steel to form a generally cylindricalwafer, (b) heat treating said wafer to provide it with a desiredhardness, (c) grinding said wafer to form a properly dimensioned heattreated blank wafer for use in forming the roller.
 2. The process ofclaim 1 further including the steps of:(d) a second grinding of saidwafer to form a finished shape of a heat treated roller, (e) vibratoryfinishing said roller to achieve a desired microfinish thereon.
 3. Theprocess of claim 2 wherein said finished roller is laser etched withinformation regarding identification, material and heat treatinghardness.
 4. The process of claim 2 wherein said second grinding isperformed by a CNC centerless grinding machine.
 5. The process of claim1 wherein said heat treating step is carried out in a vacuum.
 6. Theprocess of claim 1 wherein said heat treating step is carried out toachieve a hardness in the range of about 63 to about 70 on a Rockwell CScale.
 7. The process of claim 1 wherein said tool steel selected fromthe group consisting of: CPM-REX 76, ASP-60 M-2, and ASP-60 M-4.
 8. Aprocess for manufacturing an upper work roller for use in the deeprolling of crankshafts or like products, comprising the steps of:(a)rough sawing tool steel to form a generally cylindrical wafer, (b) heattreating said wafer to provide it with a desired hardness, (c) grindingof said wafer to desired dimensions to form a properly dimensioned heattreated blank wafer, (d) a second grinding of said wafer to form afinished shape of work roller, (e) vibratory finishing said roller toachieve a desired microfinish thereon.
 9. The process of claim 8 whereinsaid second grinding is performed by a CNC centerless grinding machine.10. The process of claim 9 wherein said heat treating step is carriedout in a vacuum.
 11. The process of claim 8 wherein said heat treatingstep is carried out to achieve a hardness in the range of about 63 toabout 70 on a Rockwell C Scale.
 12. The process of claim 8 wherein saidtool steel is selected from the group consisting of: CPM-REX 76, ASP-60M-2, and ASP-60 M-4.
 13. A process for manufacturing an upper workroller for use in the deep rolling of crankshafts or like products,comprising the steps of:(a) rough sawing tool steel to form a wafer, (b)heat treating said wafer to provide it with a desired hardness, (c)grinding of said wafer to desired dimensions to form a properlydimensioned heat treated blank wafer, (d) a second grinding of saidwafer to form a finished shape of work roller, and wherein, said heattreating step is carried out to achieve a hardness in the range of about65 to about 67 on a Rockwell C Scale, and said second grinding step isperformed by a CNC centerless grinding machine.
 14. A process formanufacturing an upper work roller for use in the deep rolling ofcrankshafts or like products, comprising the steps of:(a) retrieving apreviously heat treated and properly dimensioned generally cylindricalwafer from storage, (b) grinding of said wafer to form a finished shapeof a heat treated roller, (c) vibratory finishing said roller to achievea desired microfinish thereon.
 15. The process of claim 14 wherein saidgrinding is performed by a CNC centerless grinding machine.
 16. Theprocess of claim 15 wherein said heat treating step is carried out in avacuum.
 17. The process of claim 16 wherein said heat treating step iscarried out to achieve a hardness in the range of about 63 to about 70on a Rockwell C Scale.
 18. The process of claim 17 wherein said toolsteel is selected from the group consisting of: CPM-REX 76, ASP-60 M-2,and ASP-60 M-4.
 19. The process of claim 18 wherein said finished rolleris laser etched with information regarding identification, material andheat treating hardness.